Although the sweet potato is an exotic, tropical root crop from South America, it is becoming an increasingly common sight in our local supermarkets. Nutritious and easy to grow, you can plant it just about anywhere so long as the soil is free draining and the plant gets plenty of sun.

Generally pest free in the northern European countries, the only problem that you likely to get with growing sweet potatoes is slug damage, and this is why the practice of growing them in containers is becoming a far more popular method.

Being grown in a pot has other benefits too because not only will it provide better drainage than it would otherwise get in the ground, it will also afford warmer soil temperatures as the pot can transfer heat from the sun directly into the root environment. Both of these factors help to create improved growing conditions.

To make the most of the growing season your crop can be started off indoors by planting slips (rooted sweet potato cuttings) or tubers into as large a pot as you can physically move around. This will need to be done approximately 3-4 weeks before the last frost - which in the United Kingdom will mean planting from the beginning of April onwards.

They will require a rich, free-draining compost and you can create this by using good quality garden topsoil, horticultural grit and well rotted farm manure mixed together using a 1:1:1 ratio. Slips should be planted at the same depth that they were lifted from, while tubers should be planted on their side at a depth of about 6 inches. To give you a rough idea of spacing you can plant 3 slips/tubers in an 18 inch diameter pot.

Being a semi tropical plants they require at least 110 days to mature. They are vigorous, and once they start growing, will readily spread. You can choose to control the vines by growing them vertically up a wigwam or trellis or allow them to trail naturally along the ground.

They can be lifted from the end of August, but it is usually better to leave them until the leaves begin to yellow and die back. In fact, you can leave them in the pot for as long as you can so long as they are not damaged by early frosts. Once lifted, the new tubers will need to be allowed to mature for a week or so in the warmest area you have in the house - something like the airing cupboard will be fine. This will allow the skins to ripen and the flavour to sweeten and become true to type. They are now ready for use in cooking and will store quite happily in a cool dry place for a month or so.

Although it may seem a little premature to start on your seeds when your plot is probably still under a thick layer of snow, it is well worth starting a few things off before the sowing madness of February arrives.

Of course you are going to be a little limited as to what you can grow this early on, but indoor sowings of onions and pepper varieties are just the thing for getting your eye back in. Don't forget the king of winter sowing - broad bean 'Aquadulce Claudia'!

Onions

January is the ideal time for growing onions from seed. Sow them into either plugs or a seed tray containing a good quality John Innes ‘seed’ compost. Give the seeds a light covering of the same compost and gently water them in. Germination of onion seeds will take between 14-21 days but they will need to be kept at a temperature of about 19-21C during this period. This is important as higher temperatures can inhibit germination.

Once the seedlings get to about 1 ½ inches high they can be transplanted into individual 3-4 inch pots, but make sure that the tiny bulb is not covered by the compost. In a couple of weeks - once the new seedlings are well rooted into their pots - they can be moved outside into a cold frame to harden off. A few weeks more and they will be ready for planting out into their final position.

Plant the seedlings in early spring into a sunny position that has a rich, well drained soil - preferably it would have had plenty of well rotted compost dug in to it the previous autumn. Keep them at about 5 inches apart and add a dressing of general fertiliser just before planting.

This covers most of the varieties for northern Europe if you wanted to grow them outside. Starting them off early as a protected crop is essential because if you waited until after the last frosts the resulting summer season will neither be long or warm enough for them to crop decently before the onset of winter.

Sow your pepper seeds - adequately spaced - into either plugs or a seed tray containing John Innes ‘seed’ compost. Top them off with another 1/2 inch of compost then gently water them in. It's important that the seeds remain moist until they germinate and as such will require adequate ventilation to prevent fungal rots. If ventilation is poor you may need to spray your newly germinating seedlings with a liquid fungicide once a week to protect them.

Once germinated – this will be normally between 7 and 24 days - pepper seedlings will require plenty of light, in fact for optimal growth they will need between 12 to 16 hours of light a day. If the weather isn't yet suitable for planting outside then they will need to be placed onto a south-facing windowsill but remember to turn them daily to keep them from acquiring a permanent lean.

Once the seedlings have produced four leaves they will be ready to prick out into individual pots, but you need to be careful so as not to damage the fragile root system. The safest way is to gently hold onto one of the sturdier leaves while using either a pencil or slim dibber to lift the roots as intact and undisturbed as possible. When re-potting, use either a standard multi-purpose compost or John Innes ‘No.1’ or ‘No.2’ potting compost.

Grow them on for another couple of weeks and they will be ready for either the greenhouse or for planting directly outside into open ground once the threat of frosts is over. Make sure you choose a location that is in full sunlight and - if you have it - mix in some mushroom compost or other organic compost to help keep the soil fertile and moist.

So long as the ground isn't frozen you can direct sow broad bean 'Aquadulce Claudia' Seed outdoors under cloches from early autumn to late winter.

They will require full sun on rich fertile, well manured soil with protection from strong winds. Plant broad beans 'Aquadulce Claudia' in double rows set 9 inches apart and allowing a minimum of 24 inches between each double row. Sow broad bean seeds at a depth of 2 inches and water well. You can expect germination to occur in around 10 days.

As the plants mature, support them by placing a cane or stout stick at each corner of a double row and tying them in with string. This is particularly important in windy gardens. Keep them well watered, particularly as flowers begin to set and hoe between rows regularly. Pinch out the growing tips after the first flowers have set their pods as this will not only deter blackfly but will also encourage further bean pods to set. Harvest broad beans when the pods are well filled and the beans inside are still soft.

To begin with - if you get a choice - choose the largest, healthiest specimen that you can find, discarding anything that is showing signs of disease.

Butternut squash seeds

When it comes to harvesting squash seeds, you must wait until the fruit is ripe and ready for eating. To be on the safe side you can leave them indoors on a warm windowsill for day or two to allow the seeds to develop further.

Once you are happy that the squash is ready, cut it open, scoop the seeds out into a sieve and rinse them under a running cold tap. This will wash off most of the fibrous, jelly like coating which covers them – this is there to prevent germination while they are still in the fruit.

Once clear of the fibrous jelly, spread the seeds out onto a china plate to dry - then after a couple of days turn them over. It is important to allow them to dry out thoroughly although this can a few weeks. This is important because you do not want the seed to rot while they are in storage.

Once properly dry, store in an airtight container and place in a cool dark place where they can remain viable for up to five years.

Originating from an area around Mexico, the butternut squash has proven itself to be a popular vegetable with both chefs and gardeners alike. Roasted, toasted or mashed into soups, casseroles or breads the butternut squash is extremely versatile, and so it’s no wonder that it is becoming an increasingly common find in our vegetable gardens and allotments.

Growing butternut squash from seed is a relatively simple affair as the resulting seedlings are normally quite vigorous. You could of course prepare and save the seed from supermarket bought specimens but if you live in a northern European climate you will need to grow varieties that can cope with our comparatively shorter growing period.

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Butternut squash

In recent years there have been several trials to find out which varieties perform best with regards to vigour, flavour, and cropping. In fact the Royal Horticultural Society have completed their own trials and have recommend the AGM (Award of Garden Merit) to the cultivars ‘Hunter’, 'Cobnut’, ‘Harrier’ and ‘Hawk’.

You should begin sowing in May using 3 inch pots filled with the bottom inch or so filled with in a good quality John Innes seed compost, but if you have a tendency to over-water then you may wish to add a handful of horticultural grit to the mix to improve the drainage. Take one seed and place it either on its side, or with the pointed end down, then fill the pot to within 1 inch of the top with more of the compost mix.

Water in and then place your pots onto a warm, sunny windowsill. The seedlings should emerge within 7 – 10 days. Now these new plants will grow pretty fast from this point and so it’s important that they don’t dry out – they will probably need watering every 2-3 days, but make sure that they don’t become water-logged otherwise fungal rots could appear. Even at this stage you can consider feeding ½ the recommended dosage of an appropriate liquid fertiliser.

After about four weeks on from sowing, your squash seedlings should be ready to go outside, but they will need to be hardened off for a week or two before being left in their permanent position. You have two choices at this point. So long as the threat of late frosts are over you can either plant directly into the ground or – if you are short of space – plant into large containers, but when it comes to butternut squash, the larger, the better!

Producing slips from sweet potato tubers is relatively easy, but to make the most of your growing season you will need to start propagation 3-4 weeks before your last frosts which in the United Kingdom can mean starting any time from the end of February.

To begin with you will need a good free draining compost, and this can be made by taking standard seed compost and adding to it an equal part of horticultural grit to give you a 1:1 grit/compost mix. The next thing to do is to take this new mix and add it to a deep and reasonably wide pot or seed tray..
Take your fresh, disease-free sweet potato tuber and plant it on its side in its container before giving it a good water.

Keep the planted container in a warm location - such as a windowsill above a radiator - preferably at a temperature of between 20- 25 degrees Celsius. Keep the compost watered during this growing period but take care to make sure that it does not become waterlogged. New shoots, known as slips, should appear in two to three weeks, and as soon as they are showing three to four healthy-looking leaves they will be ready to be separated from the parent for use as propagation material.

Using a sharp and sterile knife, carefully remove the slips from the main tuber. Each slip will have its own set of roots attached and these will need to be kept as intact as possible.

If there is no longer a threat of frost then you can plant these rooted slips outside once soil temperatures reach over 20 Degrees Celsius, ideally, plant under a cloche or fleece tent for that little extra protection – but this can be removed after a few weeks.

They will require a very fertile but light, and preferably sandy soil. If your soil is not naturally free-draining, then it is worth planting your slips into ridges 6-12in high, with 2-3ft between each row. Each plant should be spaced 12-18in apart on each ridge.

Alternatively you can try using longer 12 inch slips, removing all but the tiny leaves at the very tip. Plant the cutting by covering the whole length with soil, only the leaves of the tip should stick out of the ground. The cuttings will root at every leaf node. Not just the leave nodes under the ground will root. A sweet potato also grows roots from every leaf node that develops as your cutting grows. This time leave 2-3 ft gap between slips..
Once the newly planted slips begin to take off keep them well watered and feed weekly with a high potash fertiliser.